BELL RINGER What is the area of a regular decagon if its side length is 12 m and its apothem is 5m?...

BELL RINGER

• What is the area of a regular decagon if its side length is 12 m and its apothem is 5m?

• Suppose the perimeter of some n-gon is 230 feet. If the area of the n-gon is 600 square feet, what is the length of the apothem?

Examples Cont’d

3cm

If the area is 45 cm2, what is the side length of the regular hexagon? What is the perimeter?

Surface Area

New definitions, Finding Surface Area, and Examples . . .

Surface Area

• To find the area of a 3-dimensional figure, you will need to find it’s SURFACE AREA. You will do this by finding multiple areas of the figure and adding them all together. We will investigate:– Prisms– Pyramids– Cylinders– Cones

Faces

• Any 3-d figure will have multiple ‘faces’ that create the overall figure. Observe p. 445 in book, and view in class example.

• The face on the bottom is called the ‘base’.

• The faces that are not a base are called ‘lateral faces’.

To find Surface Area

• Draw a picture of each face and label its lengths.

• Calculate the area of each face.

• Add the area of each face together.

Examples

• See board.

Class Work

• P. 450, #1-9, 11

If you finish early,

p. 455, #1-10